scholarly journals Ultrahigh‐cell‐density heterotrophic cultivation of the unicellular green microalga Scenedesmus acuminatus and application of the cells to photoautotrophic culture enhance biomass and lipid production

2019 ◽  
Vol 117 (1) ◽  
pp. 96-108 ◽  
Author(s):  
Hu Jin ◽  
Hu Zhang ◽  
Zhiwei Zhou ◽  
Kunpeng Li ◽  
Guoli Hou ◽  
...  
Keyword(s):  
Cell Density ◽  
Lipid Production ◽  
Photoautotrophic Culture ◽  
Heterotrophic Cultivation ◽  
Green Microalga ◽  
Scenedesmus Acuminatus

scholarly journals Trophic Transition Enhanced Biomass and Lipid Production of the Unicellular Green Alga Scenedesmus acuminatus

2021 ◽  
Vol 9 ◽  
Author(s):  
Hu Zhang ◽  
Liang Zhao ◽  
Yi Chen ◽  
Mianmian Zhu ◽  
Quan Xu ◽  
...  
Keyword(s):  
Algal Cell ◽  
Lipid Production ◽  
Reducing Power ◽  
Transition Process ◽  
Tca Cycle ◽  
Carotenoid Biosynthesis ◽  
Microalgal Biomass ◽  
Lhc Ii ◽  
Heterotrophic Cultivation ◽  
Scenedesmus Acuminatus

Microalgal heterotrophic cultivation is an emerging technology that can enable producing high cell-density algal cell cultures, which can be coupled with photoautotrophic cultivation for valuable chemicals such as lipids manufacturing. However, how the heterotrophically grown algal cells respond to the lipid-inducing conditions has not been fully elucidated so far. In this study, when the heterotrophically grown Scenedesmus acuminatus cells were subjected to the high light (HL) and nitrogen-limited (NL) conditions, both the biomass and lipid productivity were enhanced as compared to that of the photoautotrophically grown counterparts. The chlorophyll a fluorometry analysis showed that the Fv/Fm and Y(II) of the heterotrophically grown cells subjected to the HL and NL conditions was recovered to the maximum value of 0.75 and 0.43, respectively, much higher than those of the photoautotrophically grown cells under the same stress conditions. Transcriptomic analysis revealed that heterotrophically grown cells fully expressed the genes coding for the photosystems proteins, including the key photoprotective proteins D1, PsbS, light-harvesting-complex (LHC) I and LHC II. Meanwhile, downregulation of the carotenoid biosynthesis and upregulation of the glycolysis/gluconeogenesis, tricarboxylic acid (TCA) cycle and oxidative phosphorylation pathways were observed when the heterotrophically grown cells were subjected to the HL and N-limited conditions for lipid production. It was deduced that regulation of these pathways not only enhanced the light utilization but also provided the reducing power and ATP by which the biomass accumulation was significantly elevated. Besides, upregulation of the acetyl-CoA carboxylase/biotin carboxylase, digalactosyl diacylglycerol synthase and diacylglycerol acyltransferase 2 encoding genes may be attributable to the enhanced lipid production. Understanding the cellular responses during the trophic transition process could guide improvement of the strength of trophic transition enhancing microalgal biomass and lipid production.

scholarly journals Draft Genome Sequence of the Green Alga Scenedesmus acuminatus SAG 38.81

2020 ◽  
Vol 9 (24) ◽  
Author(s):  
Yekaterina Astafyeva ◽  
Malik Alawi ◽  
Daniela Indenbirken ◽  
Dominik Danso ◽  
Adam Grundhoff ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Genome Sequence ◽  
Draft Genome ◽  
Whole Genome Sequence ◽  
Whole Genome ◽  
Content Type ◽  
Green Microalga ◽  
Scenedesmus Acuminatus ◽  
Valuable Compounds ◽  
Β Carotene

ABSTRACT Scenedesmus acuminatus, also known as Tetradesmus acuminatus, is a promising green microalga for sustainable production of microalga products, including valuable compounds such as astaxanthin, β-carotene, and lutein, polysaccharides such as β-glucan, and polyunsaturated fatty acids. Here, we report the draft whole-genome sequence of Scenedesmus acuminatus SAG 38.81.

scholarly journals Fast media optimization for mixotrophic cultivation of Chlorella vulgaris

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Valerie C. A. Ward ◽  
Lars Rehmann
Keyword(s):  
Cell Density ◽  
Lipid Content ◽  
Lipid Accumulation ◽  
Accumulation Rate ◽  
Lipid Production ◽  
Total Lipid Content ◽  
Mixotrophic Cultivation ◽  
Cell Weight ◽  
Dry Cell Weight ◽  
Dry Cell

AbstractMicroalgae can accumulate large proportions of their dry cell weight as storage lipids when grown under appropriate nutrient limiting conditions. While a high ratio of carbon to nitrogen is often cited as the primary mode of triggering lipid accumulation in microalgae, fast optimization strategies to increase lipid production for mixotrophic cultivation have been difficult to developed due to the low cell densities of algal cultures, and consequently the limited amount of biomass available for compositional analysis. Response surface methodologies provide a power tool for assessing complex relationships such as the interaction between the carbon source and nitrogen source. A 15 run Box-Behnken design performed in shaker flasks was effective in studying the effect of carbon, nitrogen, and magnesium on the growth rate, maximum cell density, lipid accumulation rate, and glucose consumption rate. Using end-point dry cell weight and total lipid content as assessed by direct transesterification to FAME, numerical optimization resulted in a significant increase in lipid content from 18.5 ± 0.76% to 37.6 ± 0.12% and a cell density of 5.3 ± 0.1 g/L to 6.1 ± 0.1 g/L between the centre point of the design and the optimized culture conditions. The presented optimization process required less than 2 weeks to complete, was simple, and resulted in an overall lipid productivity of 383 mg/L·d.

scholarly journals Enhanced Lipid Production and Molecular Dynamics under Salinity Stress in Green Microalga Chlamydomonas reinhardtii (137C)

Marine Drugs ◽  
2019 ◽  
Vol 17 (8) ◽  
pp. 484 ◽  
Author(s):  
Thanapa Atikij ◽  
Yolani Syaputri ◽  
Hitoshi Iwahashi ◽  
Thanit Praneenararat ◽  
Sophon Sirisattha ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Chlamydomonas Reinhardtii ◽  
Saturated Fatty Acids ◽  
Lipid Production ◽  
Acid Methyl Ester ◽  
Biodiesel Production ◽  
Induced Stress ◽  
Green Microalga ◽  
Microalgal Lipids

Microalgal lipids are a source of valuable nutritional ingredients in biotechnological industries, and are precursors to biodiesel production. Here, the effects of salt-induced stresses, including NaCl, KCl, and LiCl stresses, on the production of lipid in green microalga Chlamydomonas reinhardtii (137c) were investigated. NaCl stress dramatically increased saturated fatty acids (SFAs), which accounted for 70.2% of the fatty acid methyl ester (FAMEs) under stress. In contrary, KCl stress led to a slight increase in SFAs (47.05%) with the remaining being polyunsaturated fatty acids (PUFAs) (45.77%). RT-PCR analysis revealed that the genes involved in FA biosynthesis, such as PDH2, ACCase, MAT and KAS2, were up-regulated by NaCl-induced stress. Conversely, the genes responsible for the Kennedy pathway were suppressed. The alteration of FA homeostasis was further assessed by overexpressing MAT, the enzyme responsible for the production of malonyl-ACP, a key building block for FA biosynthesis, in the cyanobacterium Synechococcus elongatus PCC 7942. Intracellular FA composition was affected, with a predominant synthesis of SFAs in transformed cells. Owing to the diversity and relative abundance of SFAs, monounsaturated fatty acid (MUFAs) and PUFAs enable the feasibility of using microorganisms as a source of microalgal lipids or valuable nutritional ingredients; salt-induced stress and expression of MAT are useful in providing precursors for enhanced lipid production.

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